When math is fun
Yes, there will be a quiz following this column.
“The required length for the sheet of the square sail above the one you want to set (L) equals the width of the yard of the lower sail (w) plus the height of the yard of the higher sail minus the height of the yard of the lower sail (δh)plus the square root of the width of the lower yard squared plus the height of the higher yard minus the height of the lower yard squared.”
L = w + m – δh + √(w²+δh²)
It all started when Klaas challenged us to predict in how much time we would have the sun straight above us. Since we're catching up with the imaginary line on the face of the earth to which the sun is perpendicular, there will be a moment in which we cross it. Who gets it right, wins a price. So, people started counting, checking tables and just wildly guessing. By the way, I wrote a haiku about being straight under the sun.
On playful trade winds
the masts' shadows disappear.
We cruise past the sun.
But the calculations didn't stop. Last night, my buddy at the helm asked me: so why do we cast off the sheets of the royal when we're setting the topgallant? We actually already knew they would be blocking the hoisting of the yard when not released, but we were a little fuzzy on the mechanics. Basically, by raising the yard, there is a part of the line you increase in length, and a part that gets shorter. That's why this morning I started drawing and formulating. For the first time in ten years I felt the need for a calculator to plot a graph.
We figured it out. And yes, from our formula it follows that in order to raise a yard you need to increase the length of the sheets of the sail above it.
Sailing. It's got everything.